The role of sub-continental lithosphere mantle in deep F and Cl cycling:Insight from the Dabeigou basalts,North China Craton  

作　　者：Yadong WU Jinhui YANG Jinfeng SUN Hao WANG Baoquan ZHOU 

机构地区：[1]State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [2]College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China [3]Key Laboratory of Computational Geodynamics,University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Science China Earth Sciences》2025年第2期564-580,共17页中国科学(地球科学英文版)

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.42288201,42003029,42322203,42303027,and 42073034)。

摘　　要：The sub-continental lithosphere mantle(SCLM)represents a mechanical barrier that separate the convecting mantle from the exosphere,and possesses the ability to sequester and release volatiles,making it an integral part in deep volatile cycling.Here we explore the SCLM in modulating F and Cl cycling through a case study from the Early Cretaceous Dabeigou basalts in the North China Craton(NCC).These lavas are associated with decratonization of the NCC,a process involving significant removal and replacement of the ancient SCLM.The Dabeigou basalts,characterized by arc magma-like trace element signatures,evolved initial^(87)Sr/^(86)Sr(0.70574–0.70578),ε_(Nd)(t)(-11.2–-11.1),andε_(Hf)(t)(-13.7–-13.4)values,along with high Fe/Mn ratios,Ni contents,andδ^(18)O values(5.8‰–6.8‰)of olivine phenocrysts,are compatible with their origination from a veined,pyroxene-rich source formed through the infiltration and interaction of hydrous silicate melts from the subducting Pacific slabs with ambient SCLM.Olivine-hosted melt inclusions of the Dabeigou basalts have compositions similar to the whole rocks,indicating that they record pre-eruptive melt compositions forming the whole rocks.The melt inclusions exhibit high F(1371–2316 ppm)and moderate Cl(688–900 ppm)contents,with high F/Cl ratios of 2.1±0.3(1σ).The F and Cl signatures of the Dabeigou basalts are different from those of typical arc magmas,which are commonly characterized by high Cl contents(median of~1200 ppm)and low F/Cl ratios(<1).The observed differences can be attributed to chromatographic reaction that fractionates elements of different compatibility in the metasomatic agents,with amphibole as the main mineral phase for fractionating and preserving F and Cl.That is,amphibole crystallization prefers to retain F rather than Cl,making the metasomes in vein enriched in F and exhibiting elevated F/Cl ratios compared to original metasomatic agents.It is further suggested that the scenario inferred from the Dabeigou basalts might be common for crystalli

关 键 词：North China Craton Sub-continental lithosphere mantle Early Cretaceous Dabeigou basalts Melt inclusion F and Cl cycling 

分 类 号：P542.5[天文地球—构造地质学] P588.145[天文地球—地质学]